Electric motor control



July 20 1926. I

H. c. HASTINGS ELECTRIC MOTOR con'mo1.

Filed uovfls, 192:

Contactans.

Inventor: Hammond Cfflast/n 8,

M's/466 or'n fy Patented July 20, 1926.

UNITED STATES.

PATENT OFFICE.

HAMMOND cnAR-nns HASTINGS, on RUGBY, nnonnnn, nssmnon TO GENERAL nnno'rmo COMPANY, A oonronnrron on NEwYonx.

nun-cram. MOTOR conrnon ppueaumand November 13; 1923, Serial No. 674,58 and in Eng and December 15, 1922..

Thi invention relates.- to. improvements in s stems of electric motor control wherein t e contactors for controllin I the starting resistance and the series paral e1 connections of the motors; are operated by cams mounted on a shaft.

According to. the present: invention, I utilize one or more, ofthe camv operated contactors. as circuit, breakers, these circuit breakers being closed b camsv on the cam shaft.v and, retained in tiieir closed position y means; of shunt. excited. solenoids. One

advantage of thisarrangemcntis that the retaining solenoids for the contactors may be made much, smaller than Where the solenoid has to: uaovethcv contactor to its closed position.

According to the. present invention, the circuit breaker contaotor is. closed the. cam onthe camshaft, when in its oil position, but this does not complete the main ciromit. of the motors, as, a. line contactor is roviclecl which is onlycloscd after the; cam {llaft has; moveclaway from the off position and before this, line contactor is closed, the cam which has closed the circuit breaker is moved, out of contact with. it so that the circuit breaker is free to open if its retaining coil is, deencrgized. i

The carnorcarns used. for closing the, cin cuit breakers never occupy a position which will interfere with, the, opening of the breakers. for any position ot the cam shaft in which the circuit of the motors is closed, so that, the circuit breaker is. free. to

open should an overload, occur during the starting or. running, Au. overload relay is used withthe circuit breaker, and this relay when operated by an overload is latched in its tripped position and is .rovided, with contacts which Will in this position, open the retaining coil of the breaker and arrest the forwardbperation of the cam shaft. The circuit breaker contactor is also used as the line, contactor for opening the circuit Whenever the master controller is returned to its off position, as this movement of the master controller will deenergize the retaining coil of the breaker. A motor may be provided for operating the cam shaft and the opening of the breaker causes the cam shaft to return to its off position. and again close the breaker, The main circuit is still open under these conditions, as the contactor which closes the line circuit has been opened When. overload occurs, if the, master controller is, still retained in one of the op erative positions,.such as, a starting or running position, the. breaker will trip and. the: cam shaft. motor vvill run the. cam. shaft back to the oifpositio-n, where. it. will. remain until ti o overload relay has been reset. Contacts on the overload. relay cause the forward running circuitof the cam shaft motor to open, when the relay is tripped. so that the motor can only run tov the off position until the relay has been reset. To: reset. this relay the control switch has to. be opened, and thrown to the reset position, thus energizing the. re,- set coil of the relay... Opening the control switch for this purpose. causes; the circuitv breaker. tov be opened and the. camshaft. to. be. returned to its, off position, thus ensuring, that the starting resistance will be in circuit when the motor isv switched on again.)

Where. a no-voIta-ge relay is included, contacts on this relay Will cause the, retaiiu ing coil circuit, of. the circuit breaker to be opened, when the no-volt coil of the relay is decnergized, The opening of the no-volt. relay also causes the. forward running circuit of the cam shaft motor to. be opened. and the cam shaft to return to the. ff. p 'e tion Where; it will remain. owing to. the for- Ward rumiing circuit, of the. camshaft being opened even if the master controller in, one of its running positions...

To obtain the connection for causing the cam shaft motor to. return. to. the. off posh tion, a relay operated by a shunt coil is; pro.- vided for each equipment which relay when deenergirsed completes, the return running circuit of the cam shaft motor. This relay is energized in all positionsj but the. oil. position of the master controller, and is deenergized and trips Whenever the master controlleris returned to its off position or the no-volt coilis deenergized. Contacts are provided on the cam shaft for opening the backward running circuit of the cam shaft motor, if the circuit breaker has been fully closed and the cam shaft is in its oil position.

The accompanying diagram, Figure 1, illustrates one form of this invention. In order to simplify the diagram a single series motor only has been illustrated, and as many as possible of the resistance contactors have been omitted. Figure 2 is a detail showing a portion of the contactors operated by the pilot motor.

In the drawings. 1 represents the clrcuit breaker which is closed by the cam shaft, and is retained in its closed position by a shunt coil 1". This circuit breaker has an auxiliary switch 1, mechanically connected to it, so that it is closed when the circuit breaker closes. A line contactor 2 which is also operated by the cam shaft is shown in the main circuit of the motor. This contactoris closed after the cam which closes the circuit breaker l is moved past its operative position, so that the circuit breaker is free to open if necessary.

The main resistance, motor armature, and series field are shown diagrammatically at 3, 4 and 5 respectively. In the main circuit an overload relay 6 is provided having auxiliary contacts 6 and 6 and a resetting coil 6 in a shunt circuit. A no-voltage relay 7 is also provided having two sets of auxiliary contacts "1'' and 7 The direction of rotation of the cam shaft motor is controlled by an auxiliary relay 8 and when the energizing coil of this relay is excited, the contacts are in a position to cause the motor to rotate the cam shaft to start up and run the main motor. When this coil is deenergized the contacts occupy a position which completes the circuit of the cam shaft motor for running it back to its off position.

The cam shaft carries cams which operate contacts 9 and 9. These contacts open the circuit of the cam shaft motor at the full on and off positions, 9 opening the circuit at the full on position, when the motor has been running forward and 9 opening the circuit at the off position when the cam shaft is returned far enough to completely close the circuit breaker 1.

The cam shaft motor is illustrated at 10,

'10 being the armature and 10 the field.

volt relay, the overload relay, or the circuit breaker.

In any of these cases, the relay contacts move to a position where they cause the cam shaft motor to return the cam shaft to the off position. The main circuit is always open on the contacts of the breaker 1 and closed on the contacts of the contactor 2.

The operation of the equipment will be understood from the foregoing description.

My invention is useful in the control of a train of cars operated by electric motors, wherein a controller located on one of the cars is utilized to govern control equipment on several of the cars of the train.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a system of motor control, a circuit breaker in the motor circuit, a magnet for retaining the circuit breaker in the closed position, a cam shaft controller arranged to mechanically close the said circuit breaker in the off position of the controller and release the same to be retained by the said magnet in operative positions of the controller, and a second circuit breaker included in series with the first circuit breaker in the motor circuit and arranged to be mechanically closed and maintained closed by the said controller only in operative positions of the controller.

2. In a system of motor control, a circuit breaker in the motor circuit, a magnet for retaining the circuit breaker in the closed position, a pilot motor, a cam shaft operated thereby and arranged to mechanically close the said circuit breaker in the off position of the controller and release the same to be re tained by the said magnet in operative positions of the controller, a second circuit breaker included in series with the first circuit breaker in the motor circuit and arranged to be mechanically closed and main tained closed by the said controller only in operative position of the controller, and a relay energized to operate responsivcly to abnormal conditions in the motor circuit. connected to control the said first circuit breaker and control the energization of the said pilot motor to return the said cam shaft to the off position.

In witness whereof, I have hereunto set my hand this twenty ninth day of October, 1923.

HAMMOND CHARLES HASTINGS. 

